1. Field of the Invention
The present invention is related to an optical disk recording device and an optical disk recording method to perform an OPC (Optimum Power Calibration) before recording a signal on an optical disk.
2. Description of the Related Art
In recent years, optical recording disks on the market are manufactured based on a predetermined format, but detailed specifications are different depending on the manufacturer. Therefore, an optimal recording power is different from each other. In order to solve the problem, in the optical disk recording device to record a signal on the optical disk, an OPC (Optimum Power Calibration) is performed to determine an optimal value (target value) of the recording power before recording a signal such as an image. The OPC is a process to record a signal on a PCA (Power Calibration Area), which is formed inner periphery of the optical disk, gradually changing the recording power and regenerate the recorded signal in order to determine the optimal value of the recording power.
Conventionally, the following documents are known as optical disk recording devices and optical disk recording methods to perform the OPC (Optimum Power Calibration) before recording the signal on the optical disk.
[Patent document 1] Japanese Patent Application Publication 2010-165386
[Patent document 2] Japanese Patent Application Publication 2009-129516
[Patent document 3] Japanese Patent Application Publication 2008-041128
[Patent document 4] Japanese Patent Application Publication 2007-133958
[Patent document 5] Japanese Patent Application Publication 2007-080404
[Patent document 6] Japanese Patent Application Publication 2008-108340
[Patent document 7] Japanese Patent Application Publication 2008-041139
[Patent document 8] Japanese Patent Application Publication 2004-319024
[Patent document 9] Japanese Patent Application Publication 2003-346338
The patent document 1 discloses an optical disk device and its control method. It provides the optical disk device and its control method capable of eliminating the need of correcting a reading value of a signal for every optical disk device when manufacturing the optical disk device. The paragraph [0066] discloses that “the adjusting target value of the luminescence control circuit 4 is determined by correcting the β value obtained when recording the data on the optical disk 1 or when regenerating the data recorded in the optical disk 1 by using the correction value βx so that the corrected β value becomes the target β value”.
The patent document 2 discloses an optical disk device and an evaluation method of recording quality of a data. It suggests the optical desk device and a method of selecting an OPC, with which accuracy of OPC during data recording to an unknown medium can be ensured. The paragraph [0050] discloses that “a predetermined number of β values around the β value B1, as a center, corresponding to the recommended recording power (e.g. five β values before and after the β value B1) are measured, and it is determined that both of them are linearly approximated if a distance among the measured β values is equal to or larger than a predetermined percentage (e.g. 15%) and the number of β values existing in such a predetermined percentage is equal to or larger than a predetermined number (e.g. eight β values)”.
The patent document 3 discloses an optical disk device and a method of correcting a recording power. It provides a method for correcting the recording power in real time, and to provide an optical disk device achieving high-speed recording and high quality by employing the method. The paragraphs [0031] to [0032] disclose that “the obtained β value is conducted so-called averaging process,—the obtained β value is compared with the target value (Target β)±the permissible value. As a result, when the β value is larger than the target value (Target β)±the permissible value (”Yes“: exceeding the region of the permissible value), the recording power is changed”.
The patent document 4 discloses an optical disk recording device. In the optical disk recording device, a target ratio for ROPC can be obtained properly even when bending or surface wobbling occurs in an optical disk. The paragraph [0025] discloses that “the target ratio for ROPC is determined by measuring plural pairs of β values, calculating an approximate expression of the β value and the ratio for ROPC based on the measured plural pairs of β values, and substituting the target β value into the approximate expression”.
The patent document 5 discloses an optical disk device and control method of recording power to shorten recording time and to stabilize recording quality at the same time when controlling recording power to an optical disk. The paragraph [0023] discloses that “the output power is judged to be abnormal and recording is temporarily stopped when the change rate ΔM/M0 is equal to or more than the threshold value (S108). Then, the recorded data just before stopping the recording is regenerated, and then the β value (β1) is measured by the β value detection circuit 8 (S109). And then, an uprate value α is calculated by using the measured value β1, β value (β0) and compensating rate k. α=1+k ×(β0−β1)”.
The patent document 6 discloses an optical disk recording device and a recording method of an optical disk. It provides the optical disk recording device and the recording method to select optimum recording power in accordance with property of an optical disk and then recording is performed. The paragraph [0038] discloses that “it is possible to calculate an average of β values for the recording powers Pxa-Pxj in advance, and to determine the optimal recording power Po from the approximate expression Lb4 of the plots of the average values”.
The patent document 7 discloses a disk recording/reproducing device from an alternative perspective. It provides the disk recording/reproducing device to optimally adjust the recording power of an optical beam in consideration of vibrations temporarily applied to an optical disk. The paragraph [0034] discloses that “the OPC processing part 13 obtains the β value or the jitter value based on the RF signal more than once, and determines the optimal recording power based on the average of these values when the optical disk 1a is judged to be temporarily exposed to abnormal vibrations during the OPC process”.
The patent document 4 discloses an optical disk recording device from an alternative perspective. The paragraphs [0016]-[0017] disclose that “the recording power is controlled so that the ratio of return light and recording power becomes a target value (target ratio) for ROPC that is obtained based on a target β value, which is unique for each optical disk,—as shown in FIG. 2, β values measured for each recording power slightly vary, and the average of the β values for each recording power linearly increases when the recording power is gradually increased from W1 to W4”.
The patent document 8 discloses an optical disk recording method. It provides the optical disk recording method capable of stably securing accurate recording characteristics, and recording/reproducing without errors even when there are disk mechanical fluctuation characteristics, pickup rolling characteristics or the like. The paragraphs [0014]-[0015] disclose that “the average value of the β values is 12%, the maximum value is 14%, the minimum value is 10% in the case of FIG. 6. In other words, the β value is found to vary up to 4% for the same recording laser power,—FIG. 7 shows the result of the later five sectors (11th to 15th sector) showing the recording laser power on the abscissa. FIG. 7 is a diagram showing a relation between the power before correction and the β value”.
The patent document 9 discloses a power calibration method of an optical disk device. It provides the power calibration method that is hardly affected due to variations in the circumference of a disk, without using a record region beyond one partition. The paragraph [0030] discloses that “the β value detecting circuit 8 obtains the β value of each sector by reproducing the sector area, calculates an average of the β values of each stage respectively for sectors SC05 to SC12, and then the recording laser power determining circuit 13 calculates the laser power most suitable for the recording”.
In the above described prior arts, the β value is measured for optimizing the recording power. However, if a track shift occurs when measuring the β value, the measured β value itself is shifted and the recording power cannot be optimized based on the correct β value.